Single phase Transformers: Review of Magnetically coupled circuit, Principle ofoperation, Constructional details of shell type and core type single-phase transformers, EMFequation, Losses and commercial efficiency, Conditions for maximum efficiency (Noquestion shall be set from the review portion).Salient features of ideal transformer, Operation of practical transformer under no - load andon - load with phasor diagrams. Equivalent circuit, Open circuit and Short circuit tests,Calculation of equivalent circuit parameters and predetermination of efficiency- commercialand all-day. Voltage regulation and its significance.Three-phase Transformers: Introduction, Constructional features of three-phasetransformers. Choice between single unit three-phase transformer and a bank of threesingle-phase transformers. Transformer connection for three phase operation – Star/Star,Delta/Delta, Star/Delta, Zigzag/star and V/V, Choice of connection. Phase conversion -Scott connection for three-phase to two-phase conversion. Labelling of three-phasetransformer terminals, Vector groups. Equivalent circuit of three phase transformers.
Parallel Operation of Transformers: Necessity of Parallel operation, Conditions forparallel operation – Single phase and three phase, Load sharing in case of similar anddissimilar transformers.Auto transformers and Tap changing transformers: Introduction to auto transformer -copper economy, Equivalent circuit, Three phase auto transformer connection and voltageregulation. Voltage regulation by tap changing – off circuit and on load.Tertiary winding Transformers: Necessity of tertiary winding, Equivalent circuit andvoltage regulation, Tertiary winding in star/star transformers, Rating of tertiary winding.
Transformers (continuation): Cause and effects of harmonics, Current inrush intransformers, Noise in transformers. Objects of testing transformers, Polarity test,Sumpner’s test.Direct current Generator – Review of construction, Types, Armature windings, Relationbetween no load and terminal voltage (No question shall be set from the review portion).Armature reaction, Commutation and associated problems, No load and full loadcharacteristics.Synchronous generators- Review of construction and operation of salient & non-salientpole synchronous generators (No question shall be set from the review portion).Armature windings, Winding factors, Emf equation. Harmonics – causes, Reduction andelimination. Armature reaction, Synchronous reactance, Equivalent circuit.∎
Synchronous generators (continuation): Generator load characteristic. Voltageregulation, Excitation control for constant terminal voltage. Generator input and output.Parallel operation of generators and load sharing. Synchronous generator on infinite busbars– General load diagram, O – curves and V – curves. Power angle characteristic andsynchronizing power.Synchronous generators (continuation): Effects of saliency, Two-reaction theory, Directand Quadrature reactance, Power angle diagram, Reluctance power, Slip test.
Synchronous generators (continuation): Open circuit and short circuit characteristics,Assessment of reactance- Short Circuit Ratio, Synchronous reactance, Adjustedsynchronous reactance and Potier reactance. Voltage regulation by EMF, MMF, ZPF andASA methods.Performance of synchronous generators: Capability curve for large turbo generators andsalient pole generators. Starting, Synchronizing and control. Hunting and dampers.